540-47-6Relevant articles and documents
Deamination Reactions, 42. Addition of Diazocyclopropanes to Carbonyl Compounds
Kirmse, Wolfgang,Hellwig, Georg,Chiem, Pham van
, p. 1511 - 1524 (2007/10/02)
Diazocyclopropanes (6, 38, 57) were generated in equilibrium with cyclopropanediazonium ions by base-induced cleavage of the analogous nitrosoureas in methanol.Efficient trapping of the diazocyclopropanes occurred in dilute solution with a slight excess of carbonyl compounds.The reactivity of the resulting 1-(α-hydroxyalkyl)cyclopropanediazonium ions (10) depended strongly on the α-substituents.Pinacol rearrangements predominated with aldehyde adducts, the migratory aptitudes being H > Ph > CH3.These 1,2-shifts are thought to proceed with inversion at the terminus - the preferred exo-attack of acetaldehyde at 7-diazonorcarane (38) led to the endo-ketone 40.The major product derived from the acetone adduct 22 was the epoxide 26 whose reaction(s) with metanol were also examined.The intramolecular addition of 8-diazobicyclooctan-4-one (57) gave rise to 6-methoxybicyclooct-4-en-1-ol (60).Due to steric constraints, the intermediate 58 underwent exclusive cyclopropyl-allyl transformations (otherwise a minor reaction).
Deamination Reactions, 41. Reactions of Aliphatic Diazonium Ions and Carbocations with Ethers
Kirmse, Wolfgang,Jansen, Ulrich
, p. 2607 - 2625 (2007/10/02)
Aliphatic diazonium ions and carbocations were generated by deacylation of appropriate nitrosoureas (1, 5, 9) in alcohol-ether mixtures or in 2-alkoxyethanols.Ethers were generally inferior to alcohols in capturing cationic intermediates.Formation of trialkyloxonium ions led to alkyl exchange or ring opening.The observed reactivity orders were n-butyl > isobutyl for the diazonium ions, allyl > sec-butyl > tert-butyl for the carbocations, methoxy > ethoxy and oxirane > oxetane > tetrahydrofuran for the ethers, indicating the predominance of steric effects.Neighboring group participation in 4-methoxy-1-butanediazonium ions (58) and 4,5-epoxy-1-pentanediazonium ions (74) was detectable but inefficient ( 20percent of cyclic oxonium ions).